I. Field
The present disclosure relates generally to communication, and more specifically to techniques for reporting channel quality indicator (CQI) information in a wireless communication system.
II. Background
In a wireless communication system, a Node B may utilize multiple (T) transmit antennas for data transmission to a user equipment (UE) equipped with multiple (R) receive antennas. The multiple transmit and receive antennas form a multiple-input multiple-output (MIMO) channel that may be used to increase throughput and/or improve reliability. For example, the Node B may transmit up to T data streams simultaneously from the T transmit antennas to improve throughput. Alternatively, the Node B may transmit a single data stream from all T transmit antennas to improve reception by the UE. Each data stream may carry one transport block of data in a given transmission time interval (TTI). Hence, the terms “data stream” and “transport block” may be used interchangeably.
Good performance (e.g., high throughput) may be achieved by sending each transport block at the highest possible rate that still allows the UE to reliably decode the transport block. The UE may estimate signal-to-interference-and-noise ratios (SINRs) of each possible combination of transport blocks that might be transmitted and may then determine CQI information based on the estimated SINRs of the best combination of transport blocks. The CQI information may convey a set of processing parameters for each transport block. The UE may send the CQI information to the Node B. The Node B may process one or more transport blocks in accordance with the CQI information and send the transport block(s) to the UE.
Data transmission performance may be dependent on accurate determination and reporting of CQI information by the UE. There is therefore a need in the art for techniques to accurately determine and report CQI information.